Saturday, August 13, 2016

(Because it's the end of term, I'm a bit delayed in getting the Fortnightly Book post done, and it turned out to be easier just to switch it with this one, which would usually be scheduled for tomorrow morning.)

Fourteenth Sunday of Pentecost1 Thessalonians 2:1-13; Luke 10:38-42

On Crucifixion-day, the sword pierced Your side;
You were crowned with thorns and darkness crowned the earth;
Your disciples were scattered and fled in fear.
Today baptism pours forth in grace from Your side;
You crown the Church with Your immortality;
You gather Your disciples and give them hope;
You make the world radiant by resurrection.

Today is a day of victory and joy;
our Savior has sealed us with His endless light;
reward comes to the honest lovers of God.
O Craftsman of life, You have made our lives whole,
renewing our minds, long marred by corruption,
inviting us into Your kingdom's glory:
You make the world radiant by resurrection.

August, I welcome thee and all thy hours,
The sun-burnt hours, that dance about thy car,
Thy genial breezes, and refreshing showers,
Thy morning pageantry, and evening star.
Bright are thy smiles, and blithe thy votaries are,
For thou dost bring them harvests, fruits, and flowers,
Enlivening gifts, and more enlivening far,
The laughing vine to glad their clustering bowers.
Yet, August, though these various gifts be dear,
'Tis not for these I time my thankful strain;
No; but for Phyllis! (fye, why drops this tear?)
Whom thou hast sent o'er my fond heart to reign;
Oh! may she live to pleasure many a year,
Although she live to give her minstrel pain.

Friday, August 12, 2016

The phrase 'absence of evidence is not evidence of absence' is a fairly widespread one, but its history is very difficult to trace. You can find the principle being used here and there in reasoning, of course, but the actual phrase doesn't seem to pop up before the 1990s -- and its popularity is almost certainly due to Carl Sagan (although he got it from Martin Rees). From him it spread quickly, and it tends to come up quite often in certain fields. It's fairly easy to find in geology, medicine, and criminology, in particular. Discussion for and against also shows up a lot in apologetical circles, whether the apologetics is of Christians or of skeptics out to convince the masses -- I'm fairly sure that this is just because both of these groups have read a lot of Carl Sagan.

Both groups are mixed, but the Christians tend generally to be for it and the skeptics against it, if you're interested. Reading some of the skeptical discussions makes for hilarity, at times, because they are so often vehemently committed to the phrase encapsulating a fallacy, often calling it the fallacy of appeal to ignorance, or the argument from ignorance, because they associate it with UFOers, that they cannot believe that he endorses it, even though anyone with basic reading skills can see that he does.

A distinction is sometimes made between 'Absence of evidence is not evidence of absence' and 'Absence of proof is not proof of absence'. This is a post-Sagan distinction (Sagan uses 'evidence' and 'proof' interchangeably when the phrase comes up), and has come about very certainly because of the spread of accounts of evidence based on interpretations of probability theory (rather than on practices of inquiry), which as generally proposed require that absence of evidence be evidence of absence. And in fact the distinction doesn't salvage anything unless one has a very specific kind of account of proof in mind; in a lot of areas what is called 'proof' just is clear preponderance of evidence, and (on the other side) it's not actually difficult to find or rig situations in which an absence of proof would indeed be a proof of absence.

There's little serious philosophical examination of the maxim, although one can find some. Elliott Sober has argued (in "Absence of evidence and evidence of absence: evidential transitivity in connection with fossils, fishing, fine-tuning and firing squads") that while the Absence Maxim can be true if it just means that not looking for evidence is not evidence of evidence, it is not strictly true in general, although it is often close to true: in such cases the maxim should in strictness be 'Absence of evidence often only very weakly provides evidence of absence', but we often treat very weak evidence as if it were nonevidence. (Contrary to Michael Strevens's response (PDF), I don't think it is quite accurate to treat this as conveying "an underlying meaning that contradicts its apparent meaning". Sober is certainly right that we often treat making a very small difference as making no difference; and it is undeniable, I think, that most of the time when people say, "There is no evidence for p," what they mean is, "Any evidence for p is so weak as to be negligible." On Sober's account, we could add 'for practical purposes' to the Absence Maxim and get something at least in the neighborhood of right; and this seems very different from an actual contradiction.)

Let's call 'Absence of evidence is not evidence of absence' the Absence Maxim to simplify things. There are a number of distinct but related issues tangled up with the Absence Maxim that have never really been untangled; I don't hope to do so here, but it might be worthwhile to point out a few things that do seem constantly to arise.

(1) The first and most obvious thing is that the Absence Maxim gets its plausibility from the way it is structured. To be absent is simply to be not present, presence has to be presence of something, and evidence is always evidence for soemthing, so we could rephrase it as 'Evidence-for-X is not present' is not 'There is evidence for X-is-not-present'. If one were to deny this, there would be obvious questions, since the kind of shifting around of operators and scope that this involves usually suggests an equivocation. One would at least need a principled reason for denying the Maxim that shows that you aren't just trading on ambiguity. One obvious worry is how you get the existence of something (evidence for X-is-not-present) entirely from the nonexistence of something else (evidence for X). Where does the existential operator pop out from?

This, I take it is related to the issue raised in the following video by Ian Goddard, which argues that it is important to make a distinction between absence of evidence and negative evidence:

There is little doubt that you can have logical systems in which denial of the Absence Maxim is required under some interpretation (Bayesian interpretations of probability theory are common examples); but, as one can make all sorts of formal systems with all sorts of arbitrary assumptions, and interpret them all sorts of different ways, this does not get us very far on its own. The point is that any formal representation of a denial of the Absence Maxim raises questions that would require principled answers, and that these answers are not necessarily immediately obvious. And they will not fall out of the formalism itself at all.

(2) We do clearly recognize cases where absence of evidence is indeed evidence of absence -- call these negation-as-failure cases. If I thoroughly search my room for a dog and discover no evidence at all that there is a dog, then that is indeed evidence that there is no dog in my room.

One of the things that characterizes obvious negation-as-failure cases is that they are cases in which either (A) we can reasonably guarantee that our search has been exhaustive (the closed world assumption), or (B) we can reasonably conclude that further search is increasingly unlikely to turn up anything fundamentally different from what we have already discovered, so that we can discount as unpromising whatever we have not yet searched (which is a practical closed world assumption). There are many cases, however, in which we cannot guarantee any kind of closed world assumption -- for instance, if I have been searching for a dog in the city for two minutes and have not yet found it, this search was neither exhaustive nor reasonably extensive, and most people, I imagine, would regard someone as an idiot if they concluded from such a cursory search that there was no dog in the city. And as with cursory searches, so with searches that are incomplete for other reasons than merely trying.

We are sometimes in situations in which we already know that our bank of available evidence is missing a lot. Indeed, we are often in these situations -- they are the norm in most historical contexts. We already know that our fossil record does not record everything; it also does not provide a representative sample, because it only gives us things that were in fact in situations in which they, in particular, could be fossilized. Happily, there is more than one way a thing can be fossilized, but each way has its own specific conditions, and if they are not met, we don't get the fossil. Let's suppose that our fossil record is indeed very, very patchy. One way to interpret this kind of situation is to say that the fossil record, considered on its own, only provides us any evidence at all about organisms actually showing up in it, because we already know that the field of organisms and organism-types that won't show up can be massive in comparison to the field of those that do. Unless you were independently trying to fit evidence to a principle like Bayes' Theorem, there doesn't seem to be any specific reason to take an organism's not showing up in the record as evidence that it didn't exist -- most organisms that existed don't, so there's nothing about the fossil record itself that requires that you take things it doesn't show not to exist. In general this will be the case with patchy evidence; by the very fact of its being patchy, there's nothing about the collection of evidence itself that licenses taking absence of evidence as evidence of absence. The license would have to come from elsewhere.

This perhaps is connected with Sagan's own diagnosis of the problem to which the Absence Maxim is proposed as a solution -- what Sagan calls 'impatience with ambiguity'. 'Ambiguity' is a term Sagan elsewhere uses to describe the situation of not having an answer to a question. Sagan does not, as far as I am aware, explain his use of the word 'impatience' in this precise context, and Sagan is usually quite sloppy when it comes to supporting his claims about critical thinking, but I think one can argue that the term is genuinely appropriate in this context: in cases of cursory search, it is absurd to hold that not having a clear preponderance of evidence for one side is a reason to conclude it false, because you should exercise the patience required to make your investigation reasonably thorough before drawing such a conclusion rather than hurrying to draw a conclusion. There will be times in many kinds of investigation in which it will be unclear or debatable what the evidence actually shows; this is not on its own a good reason to cut short the investigation. Thus the Absence Maxim could perhaps be regarded, and sometimes seems to be used, as a non-stopping rule for inquiry -- we should not stop inquiry (even temporarily) on nothing more than the ground that we have found no evidence yet. This raises the question of how to assess the thoroughness of an inquiry. It also raises the question of the exact relation between evidence and warrant to draw a conclusion.

(3) In general, if one models inquiry as a search, it would seem to make very little sense to deny the Absence Maxim for search in general; one has to justify a negation-as-failure rule, by establishing that one's search would have picked up the evidence for something if it were there. Thus, someone who claimed that there was no extraterrestrial life because they didn't see any evidence of it when they glanced at the sky has not done the kind of search appropriate to the conclusion they are drawing. And this seems to hold even if we say that glancing at the sky would be at least a minor part of a genuinely appropriate search.

Searches are organized for different ends and can be very different in character; you cannot assume that every search is a negation-as-failure kind of search. Thus if one models inquiry as a search, there seems some reason to take the Absence Maxim to be true as a default -- one has to set up a search of the right sort to get a case in which one can conclude No X from No Evidence of X. (And note that if you relativize Bayesianism to a given kind of inquiry -- so your probability measures are always only relative to a given inquiry -- then this at least qualifies any rejection of the Absence Maxim on Bayesian grounds.) In general, if one treats the nature of the inquiry in which the evidence is being used as important to the evaluation of evidence, this seems to favor something like the Absence Maxim.

I think there does seem to be a divide in approaches to evidence, one that has not been adequately examined -- namely, between inquiry-focused and general-measure-focused accounts of evidence. There is a lot of variation within the two approaches, but the former tends to see evidence as something constructed or formed in light of an inquiry that is limited by particular ends, tends to be favorable to the idea that what counts as evidence in one field of inquiry may not always do so in another, and tends to be pluralist about how evidence supports claims (i.e., it tends not to assume that all evidential support is of the same kind), whereas the the latter tends to reject all of these things. These differences can obviously lead to some significant oppositions in how evidence is evaluated.

Thursday, August 11, 2016

Nathaniel Hawthorne, The Marble Faun
Roger Scruton, The Face of God
Sergius Bulgakov, The Lamb of God
Stephen Blackwood, The Consolation of Boethius as Poetic Liturgy
Henry Sidgwick, The Methods of Ethics

2. What book did you just finish?

Laurence Sterne, The Life and Opinions of Tristram Shandy, Gentleman
Dumitru Staniloae, The Experience of God, Volume I

I have also been reading over the past three weeks The History of Middle-Earth, which is Christopher Tolkien's study of the drafting stages of his father's works; I have finished up to Volume 10, and so have just two more volumes to go.

3. What do you plan to read next?

I don't know about next, but I'll be doing some plays by Ibsen and re-reading George Eliot's Romola at some point in the next few months. I'll be finishing Bulgakov's and Staniloae's series at some point, but that's probably a longer-term project.

I also keep meaning to get to Half Price Books, so that will doubtless turn up a few.

4. What book do you keep meaning to finish?

The Book of a Thousand Nights and a Night; I am done with two out of three volumes, 2650 pages, and just need find a time to power through the last 1300 or so pages.

National churches necessarily presuppose that the government bodies and agencies concerned with the church are legitimate representatives within the liturgical commonwealth.

homiletics as concerned with living and not merely hearing doctrine

the confusion of intellectual or volitional numbness with the doubt of genuine inquiry

Leading questions and rhetorical questions make obvious that questions can have assumptions, but that all questions have assumptions is made clear (1) by the fact that they make sense in some contexts and not others; and (2) by the fact that they distinguish relevant and irrelevant answer-candidates. (Assumptions are determined by analysis of possibilities.)

The first minimal level of making amends is simply accepting, and thus bearing and enduring, one's being responsible.

the desire to impart something genuinely precious to the world

general culture of mind as a requirement for professional life

nonmaleficence and gentlemanliness (Newman)

notional and real as poles of assent

spontaneously grown arguments vs deliberately synthesized arguments

the role of Catholic Marian piety in supporting the doctrine of papal infallibility (e.g., Lourdes)

the royal prerogatives of the Church

the problem of corruption of supplementary institutions as the primary problem of the liturgical commonwealth

Monday, August 08, 2016

Thought experiments in science are generally illuminating or, at the least, benign. It is not so with thought experiments in philosophy. They are a locus of misdirection and deception. We are supposed to derive important conclusions about fundamental matters from bizarre imaginings of zombies, who behave exactly like conscious humans, but are not conscious; or of substances that share exactly all the physical properties of water, but are not water. The narrative conventions of a thought experiment authorizes us to contemplate hokum that would otherwise never survive scrutiny.

John D. Norton, "The Worst Thought Experiment" (p. 11n). (Despite this footnote, the article is actually a criticism of Szilard's thought experiment in thermodynamics adapting Maxwell's Demon -- the worst thought experiment in science, according to Norton. As with all of Norton's philosophy of science work, the article is well worth reading.)

I think the 'important conclusions' is important here. Thought experiments in philosophy are benign, and sometimes illuminating, if they are of modest aim -- to illustrate a purely logical point, or to identify a conceptual distinction, or to exhibit a similarity between two fields of thought, or to summarize a more complicated response to a very specific point. More than this they cannot really bear. But, of course, they are made to bear more than this all the time -- when people use zombie experiments, they aren't merely sharpening the conceputal distinction between conscious experience and behavior indicative of it but treating the stories they are telling as establishing truths about consciousness itself. When you come across a philosophical thought experiment with major conclusions, always ask: What is the rational account that authorizes the inferences required by this story or description? And I think this is where they so often go wrong -- they are taken as establishing things when, at best, they can usually be doing no more than gesturing at a more sophisticated account. And, of course, very often there is no sophisticated account at all, in which case they can at best suggest a line or two of further inquiry in the same way that any metaphor or analogy might.

This is remarkably difficult to get across to some people. Just as even ordinary counterexamples must be analyzed to determine (1) that they are not merely apparent; and (2) that they are not more limited in scope than they might seem, the interior logic of a thought experiment also requires analysis, and each assumption made in building it requires examination -- it is a scaffold for further inquiry, not a primary result in its own right. But people have a weird tendency to throw out alleged counterexamples and move on, or to take thought experiments to establish things on their own. When people do this, I often just start asking the ordinary questions any sort of reader or writer of stories might reasonably ask about the logic of a tale; over and over again, one finds that the proposers of these thought experiments haven't even thought through the basic story-logic of their example, much less started working out any rigorous argument. It's a case of scaffoldings being confused with cathedrals, and means being confused with ends.

O Christ, You cast Your truth and grace abroad;
the apostles' preaching flies through the world,
their message to the far ends of the earth.
One plants, another waters, but they serve:
God does the work and God gives the increase.
The Church is the field of God's own tilling,
and all others are but His ministers.
Let us remember the sower of seed,
for seeds of truth fall on good and bad soil.

Strophe

A sower went out to sow his seed.
Some of his seed fell by the wayside,
to be trod and eaten by the birds.
Others fell on the rocks, dry and hot;
they were withered in the noonday sun.
Some fell among the thorny briars,
to be smothered by those violent weeds.
But others fell on soil of rich loam,
yielding a harvest one hundredfold.

Antistrophe

The seed is God's holy word, broadcast.
Some by the path have the seed stolen,
the devil snatching away their faith.
Some receive with joy but have no roots,
and in tribulation they wither.
Others hear but never grow to fruit,
stifled by worldly care and pleasure.
But some with bright, noble heart endure:
receiving some truth, they yield much truth.

Exode

O Lord, show your boundless mercy to us;
with Your Spirit, open our hearts to truth.
May we be pure, enlightened, forgiving,
receiving your truth with joy and honor,
nourished by the grace of living waters,
growing in love, in truth, and in mercy,
never distracted by this world's darkness,
but noble and generous in our hearts,
to yield by Your hand a harvest of grace.

Caveats

For a rough introduction to my philosophy of blogging, including the Code of Amiability I try to follow on this weblog, please read my fifth anniversary post. I consider blogging to be a very informal type of publishing - like putting up thoughts on your door with a note asking for comments. Nothing in this weblog is done rigorously: it's a forum to let my mind be unruly, a place for jottings and first impressions. Because I consider posts here to be 'literary seedings' rather than finished products, nothing here should be taken as if it were anything more than an attempt to rough out some basic thoughts on various issues. Learning to look at any topic philosophically requires, I think, jumping right in, even knowing that you might be making a fool of yourelf; so that's what I do. My primary interest in most topics is the flow and structure of reasoning they involve rather than their actual conclusions, so most of my posts are about that. If, however, you find me making a clear factual error, let me know; blogging is a great way to get rid of misconceptions.